Ink ribbon cassette

ABSTRACT

An ink ribbon cassette containing an endless ink ribbon (1) and replenishing ink to be supplied to said ink ribbon (1), and intends to stabilize PCS at an early stage of printing. For attaining the purpose, provided is an auxiliary ink supplying member (16, 32 and 42) to be brought into contact with the forward end of an ink supplier (10) for supplying ink in an ink occluding body (11) to a follower gear (7). The auxiliary ink supplying member (16, 32 and 42) is impregnated beforehand with ink to be supplied to the follower gear (7) at an early stage of printing.

TECHNICAL FIELD

The present invention relates to an ink replenishing type ink ribboncassette adapted for use in a serial printer for storing a replenishingink therein and supplying the replenishing ink to an ink ribbon by anink supplier.

BACKGROUND TECHNOLOGY

An ink ribbon cassette containing therein an ink ribbon has beenconventionally widely used so that the ink ribbon can be easily mountedon a printer and an operator's hand and the printer are prevented frombeing contaminated when the ink ribbon is mounted on the printer.

The life of the ink ribbon is in general determined by the amount of inkwhich is impregnated into the ink ribbon. However, the life of a groundfabric of the ink ribbon is normally longer than that of the ink ribbon.Accordingly, there is proposed an ink ribbon cassette provided with anink supplying means for supplying ink to the ink ribbon in order tolengthen the life of the ink ribbon.

FIG. 1 is an exploded perspective view of the ink ribbon cassettewherein an upper cover of the ink ribbon cassette and an upper cover ofan ink occluding body case are respectively removed, based on which theconventional ink ribbon cassette will be described hereinafter.

In the same figure, an ink ribbon 1, which is endless and looped, iscontained in a ribbon containing portion 3 of an ink ribbon cassette 2and the part of the ink ribbon 1 is exposed outside of the ink ribboncassette 2 from the forward ends of ribbon guide portions 4a and 4b. Theink ribbon 1 is moved in the direction of the arrow at the exposedportion.

A driving gear 5 is disposed in an inlet of the ribbon containingportion 3 and is rotatably supported by a driving gear supporting member6.

A follower gear 7 is rotatably supported by a follower gear supportingmember 8 and is pressed against the driving gear 5 by a spring 9. Teethof the follower gear 7 mesh with teeth of the driving gear 5 whileclamping the ink ribbon 1 therebetween. An ink supplier 10 formed offelt is brought into contact with the follower gear 7 at one end thereofand contacts an ink occluding body 11 formed of fiber impregnated withink at the other end thereof so as to draw ink from the ink occludingbody 11 owing to the capillary action and to supply ink to the followergear 7.

An ink occluding body cover 13 is to be attached to an ink occludingbody case 12 to prevent ink in the ink occluding body 11 from leakingout.

A ribbon cassette cover 14 accommodates all these components in theribbon cassette 2 and covers the ink ribbon cassette 2.

With such an arrangement as set forth above, the ink ribbon 1 which isclamped by the driving gear 5 and the follower gear 7 is driven by wayof the driving gear 5 when a carriage performs space driving and iscirculated and drawn in the ribbon containing portion 3 whereby the inkribbon I is contained in the ribbon containing portion 3 as it isfolded.

The ink ribbon I drawn out from the ribbon containing portion 3 ispassed through the ribbon guide portion 4a and is once exposed outsideof the ribbon cassette 2 and thereafter printing is performed throughthe ink ribbon 1. Upon completion of printing, the ink ribbon 1 ispassed through the ribbon guide portion 4b and circulated and drawn intothe ribbon containing portion 3.

When the ink ribbon I is drawn into the ribbon containing portion 3, inkfrom the ink supplier 10, which is brought into contact with thefollower gear 7, is supplied to the follower gear 7 through which ink istransferred to and replenished to the ink ribbon 1.

However, as illustrated in FIG. 2 showing the relation between thenumber of printed letters and print density, i.e. print contrast signal(hereinafter referred to as PCS), PCS is lowered at the time A at arelatively early stage of printing. This leads to such a problem thatPCS is not stabilized at the time A of the relatively early stage ofprinting.

The reason why PCS is lowered at the time A is that the amount of ink tobe supplied from the ink occluding body 11 to the ink supplier 10 doesnot overtake the amount of consumption of ink which is impregnatedbeforehand into the ink ribbon. This is described more in detail withreference to FIG. 3.

FIG. 3 is a graph showing the result of investigation of PCS usingindividually the ink ribbon and the ink occluding body. Printing by theink ribbon 1 alone means that the ink supplier 10 is removed and ink inthe ink occluding body 11 is not supplied to the ink ribbon 1 whileprinting using the ink occluding body 11 alone means that a blankribbon, which is not impregnated with ink, is used. Print density usingthe ink ribbon 1 alone and the ink occluding body 11 alone are totalledto indicate PCS in FIG. 2. As illustrated in FIG. 3, printing using theink ribbon 1 alone shows a sharp dropping of PCS while printing usingthe ink occluding body 11 alone shows that PCS increases between thebeginning of printing and five hundred thousand printed letters. Sincethe intersecting point between the line showing PCS of the ink ribbon 1alone and the line showing PCS of the ink occluding body 11 alone showsthat the number of printed letters are two hundred thousands, the reasonwhy PCS in normal printing in FIG. 2 is lowered between one hundredthousand printed letters and two hundred thousand printed letters and isincreased from five hundred thousand printed letters is that PCS usingthe ink ribbon 1 alone is sharply dropped and PCS using the inkoccluding body 11 alone is greater than PCS using the ink ribbon 1 aloneafter two hundred thousand printed letters and remains increased untilfive hundred thousand printed letters.

There is known an improvement of another ink replenishing type inkribbon cassette which is disclosed in a gazette of Japanese UtilityModel Laid-Open Publication No. 63-84362. The ink ribbon cassette asdisclosed in the gazette has an auxiliary ink supplying member inaddition to a main ink supplying member for supplying ink to the inkribbon wherein the auxiliary ink supplying member can be switched so asto be connected to or disconnected from the main ink supplying member bya switching member. That is, according to this ink ribbon cassette, thethickness of the ink supply route can be switched depending on theamount of ink residual in an ink impregnated body.

However, there are problems in this ink ribbon cassette. That is,firstly, when the auxiliary ink supplying member is forced to contactthe main ink supplying member by the switching member after PCS islowered (at point B) as illustrated in FIG. 4, the amount of ink issharply reduced thereafter so that PCS is sharply dropped. Secondly,when the auxiliary ink supplying member is forced to contact the mainink supplying member from the beginning of printing, PCS is too high atthe early stage of printing as illustrated in FIG. 5 and thereafter PCSis lowered at the relatively early stage of printing, which results inshortening the life of the ink ribbon. Thirdly, since the switchingmember should be manually operated, the switching operation istroublesome.

Accordingly, it is an object of the present invention to provide an inkribbon cassette which solves the unstableness of PCS at the early stageof printing without resorting to the manual operation for switching theink supplying means.

DISCLOSURE OF THE INVENTION

The present invention comprises an endless ink ribbon, a ribbon cassettecomprised of a ribbon containing portion for folding and containing theink ribbon therein and ribbon guide portions for exposing the ink ribbonoutside of the ink ribbon cassette from the forward ends thereof, aribbon feeding mechanism for feeding the ink ribbon from the ribbonguide portions to the ribbon containing portion, an ink supplier forsupplying ink from the forward end thereof to the ink ribbon by way ofthe ribbon feeding mechanism, an ink occluding body for supplying ink tothe ink supplier and an auxiliary ink supplying member impregnatedbeforehand with ink which contacts the forward end of the ink supplieror the ribbon feeding mechanism and is spaced away from the otherportion of the ink supplier or the ink occluding body. With such anarrangement, even if ink, which is impregnated beforehand into the inkribbon, runs out, ink in the auxiliary ink supplying member is suppliedto the ribbon feeding mechanism so that the unstableness of PCS in theearly stage of printing is solved. Furthermore, it is not necessary toperform the manual switching operation which has been made in the priorart (the gazette of Japanese Utility Model Laid-Open Publication No.63-84362). Still furthermore, since the auxiliary ink supplying memberdoes not directly contact the ink occluding body, the consumption of inkcan be saved, which results in contribution to the long life of the inkribbon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a conventional ink ribboncassette;

FIG. 2 is a graph showing the relation between the number of printedletters and PCS according to the conventional ink ribbon cassette;

FIG. 3 is a graph showing individually PCS using an ink ribbon alone andPCS using an ink occluding body alone;

FIG. 4 is a graph showing the relation between the number of printedletters and PCS according to another conventional ink ribbon cassette;

FIG. 5 is a graph showing the relation between the number of printedletters and print density according to still another conventional inkribbon cassette;

FIG. 6 is an exploded perspective view showing an ink ribbon cassetteaccording to a first embodiment of the present invention;

FIG. 7 is a top plan view showing the ink ribbon cassette according tothe first embodiment of the present invention;

FIG. 8 is a graph showing PCS according to the first embodiment;

FIG. 9 is a graph showing PCS using a blank ribbon according to thefirst embodiment;

FIG. 10 is a view showing the amount of consumption of ink according tothe first embodiment;

FIG. 11 is a graph showing amount of transmission of ink to an auxiliaryink supplier according to the first embodiment;

FIG. 12 is a plan view showing an ink ribbon cassette according to asecond embodiment of the present invention; and

FIG. 13 is a plan view showing an ink ribbon cassette according to athird embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with referenceto drawings. Elements which are common to each drawing are denoted atthe same numerals.

FIG. 6 is an exploded perspective view showing an ink ribbon cassetteaccording to a first embodiment and FIG. 7 is a plan view of the inkribbon cassette according to the first embodiment. FIG. 7 shows thestate where a cover of the ink ribbon cassette is removed.

In both figures, an ink ribbon cassette 21 according to the firstembodiment comprises an ink ribbon 1, a ribbon cassette 2 having an inkribbon containing portion 3 for containing the ink ribbon 1 therein andribbon guide portions 4a and 4b, a ribbon feeding mechanism composed ofa driving gear 5, a driving gear supporting member 6, a follower gear 7,a follower gear supporting member 8 and a spring 9, an ink supplier 10for supplying ink to the follower gear 7, an ink occluding body 11 forsupplying ink to the ink supplier 10, an ink occluding body case 15 forcontaining the ink occluding body 11 therein, an ink occluding bodycover 13, an auxiliary ink supplier 16, an ink protecting wall 17 fordividing between the ink supplier 10 and the auxiliary ink supplier 16and a ribbon cassette cover 14 for covering the ribbon cassette 2 afterall the components set forth above are contained in the ribbon cassette2.

The ink supplier 10 is formed of felt and contacts the follower gear 7at one end thereof and also contacts the ink occluding body 11 in theink occluding body case 15 at the other end thereof. The ink occludingbody 11 is formed of polyester fiber impregnated with ink. Accordingly,the ink supplier 10 sucks ink from the ink occluding body 11 owing tothe capillarity and supplies the ink to the follower gear 7. Theauxiliary ink supplier 16 contacts the forward end of the ink supplier10 at the outside of the ink occluding body case 10. The auxiliary inksupplier 16 is formed of felt like the ink supplier 10 and is beforehandimpregnated with ink.

The ink protecting wall 17 is formed between the ink supplier 10 and theauxiliary ink supplier 16 wherein both the ink supplier 10 and theauxiliary ink supplier 16 are prevented from contacting each other atthe portion other than the forward ends thereof by the ink protectingwall 17. As a result, ink in the ink occluding body 11 cannot soak intothe auxiliary ink supplier 16 but only through the forward end of theink supplier 10.

The ink occluding body cover 13 is to be attached to the ink occludingbody case 15 so as to prevent ink in the ink occluding body 11 fromleaking out as illustrated in FIG. 6.

According to the first embodiment having the arrangement as set forth,printing is performed by a print head, not shown, and the driving gear 5is rotated by a motor, not shown, so that the ink ribbon I is moved inthe direction of the arrow in FIG. 6. When the ink ribbon 1 is clampedby the driving gear 5 and the follower gear 7, ink is replenished to theink ribbon 1 from the follower gear 7.

Print density at the time of continuous printing according to the firstembodiment is illustrated in FIG. 8. As evident from FIG. 8, PCS isscarcely lowered between zero to five hundred thousand printed letters,i.e. at the time A so that high PCS, i.e. 0.7 at the beginning ofprinting is kept constant. FIG. 8 also illustrates PCS of the prior artto compare both PCS.

The reason why PCS is kept constant at the time A will be described withreference to a test data.

FIG. 9 shows the result of measurement of PCS using a blank ribbon,namely, the ink ribbon which is not impregnated with ink at allaccording to the ink ribbon cassette of the first embodiment. In thiscase, ink is impregnated into the ink supplier 10, the ink occludingbody 11 and the auxiliary ink supplier 16. As is evident from FIG. 9,PCS rises relatively quickly up to fifty thousand printed lettersaccording to the ink ribbon cassette of the present embodiment. FIG. 9also shows PCS using a blank ribbon according to the conventional inkribbon cassette. It is clear the PCS rises sharp compared with theconventional one. This shows that ink from the auxiliary ink supplier 16is supplied to the ink ribbon through the ink supplier 10 and thefollower gear 7 immediately after the beginning of printing. At the sametime, the supply of ink from the ink occluding body 11 is finally fullwhen the number of printed letters reaches five hundred thousands.

FIG. 10 is a graph showing the relation between the amount ofconsumption of ink and the number of printed letters according to thefirst embodiment wherein each relation is individually illustrated forthe ink occluding body 11 and the auxiliary ink supplier 16. As evidentfrom FIG. 10, the amount of consumption of ink of the ink occluding body11 is small between the beginning of printing and two hundred thousandprinted letters and ink, which is supplied from the auxiliary inksupplier 16, makes up such a small amount of ink.

As is evident from the explanation set forth above, PCS at the earlystage of normal printing (time A in FIG. 8) can be kept constant by thesupply of ink from the auxiliary ink supplier 16.

When ink from the auxiliary ink supplier 16 is consumed, ink from theink occluding body 11 is transmitted to the auxiliary ink supplier 16through the ink supplier 10. FIG. 11 is a graph showing the amount ofink which is transmitted from the ink occluding body 11 to the auxiliaryink supplier 16 in which the amount of transmission of ink is measuredfor the auxiliary ink supplier 16 which is not impregnated with ink. Asevident from FIG. 11, even if ink of the auxiliary ink supplier 16 isconsumed by printing, ink is transmitted to the auxiliary ink supplier16 through the forward end of the ink supplier 10 if the ink occludingbody 11 is fully impregnated with ink. According to FIG. 11, half of inkreturns to the auxiliary ink supplier 16 after ten hours lapse and inkfrom the ink auxiliary ink supplier 16 can be supplied to the ink ribbon1 in the succeeding printing.

FIG. 12 is a plan view showing a second embodiment of the presentinvention. An ink ribbon cassette 31 according to the second embodimentis provided with an auxiliary ink occluding body 32 instead of theauxiliary ink supplier in the first embodiment. The auxiliary inkoccluding body 32 is formed of the same material as that of the inkoccluding body 11, i.e. polyester fiber but may be formed of sponge ornatural wool. The auxiliary ink occluding body 32 contacts the inksupplier 10 at the forward end thereof and the ink protecting wall 17 isprovided therebetween in the same way as the first embodiment. In thesecond embodiment having such an arrangement, the same effect as thefirst embodiment can be obtained as a result of test.

FIG. 13 is a plan view showing a third embodiment of the presentinvention. In an ink ribbon cassette 41 of the third embodiment, an inkoccluding body 42 is attached to the ink supplier 10. The auxiliary inkoccluding body 42 is formed of polyester fiber and is attached to theforward end of the ink supplier 10 by an adhesive.

In the third embodiment having such an arrangement, the same effect asthe first embodiment can be obtained. In the third embodiment, since theauxiliary occluding body 42 is provided outside of the ink occludingbody case 15, the ink occluding body 11 can be enlarged, which resultsin assuring long life of the ink ribbon cassette 41.

Although the auxiliary ink supplier 16 and the auxiliary ink occludingbodies 32 and 42 are respectively forced to contact the forward end ofthe ink supplier 10, they are forced to directly contact the followergear 7 so as to increase the amount of ink to be supplied to the inkribbon 1. In this case, it is preferable to use felt as the material ofthe auxiliary ink supplying member.

INDUSTRIAL UTILIZATION

As mentioned above, the ink ribbon cassette according to the presentinvention is useful for an impact printer, particularly to a wire dotprinter and also can be used for a wire dot type line printer.

We claim:
 1. An ink ribbon cassette comprising:an endless ink ribbon; anink ribbon cassette composed of an ink ribbon containing portion forfolding and containing the ink ribbon therein and ribbon guide portionseach having a forward end for exposing the ink ribbon outside of the inkribbon cassette from the forward ends; a ribbon feeding mechanism forfeeding the ink ribbon from the ribbon guide portions to the ribboncontaining portion; an ink occluding body for storing a replenishing inktherein; an ink supplier having a forward end, said ink suppliercontacting the ink occluding body and extending therefrom to contact theribbon feeding mechanism at the forward end for supplying thereplenishing ink to the ink ribbon by way of the ribbon feedingmechanism; and an auxiliary ink supplying member which is impregnatedbeforehand with ink and contacts the ink supplier only at the forwardend of the ink supplier whereby the auxiliary ink supplying membersupplies ink, to the ink supplier or the ribbon feeding mechanism.
 2. Anink ribbon cassette comprising:an endless ink ribbon; an ink ribboncassette composed of an ink ribbon containing portion for folding andcontaining the ink ribbon therein and ribbon guide portions each havinga forward end for exposing the ink ribbon cassette form the forward endsthereof; a ribbon feeding mechanism for feeding the ink ribbon from theribbon guide portions to the ribbon containing portion; an ink occludingbody for storing a replenishing ink therein; an ink supplier having aforward end, said ink supplier contacting the ink occluding body andextending therefrom to contact the ribbon feeding mechanism at theforward end for supplying the replenishing ink to the ink ribbon by wayof the ribbon feeding mechanism; an auxiliary ink supplying member whichis impregnated beforehand with ink, said auxiliary ink supplying memberhaving an end which contacts the forward end of the ink supplier; and anink protecting wall provided between the ink occluding body or the inksupplier and the auxiliary ink supplying member for preventing ink inthe ink occluding body from soaking into the auxiliary ink supplyingmember.